The cathodic corrosion method described here is a simple, clean, and fast way of synthesizing nano-alloys :with high catalytic performance. Using a series of Pt-Rh alloys as an example, we show that thiS one-step method can convert a bulk alloy electrode into an aqueous suspension of nanoparticles;retaining the composition and crystal lattice structure of the starting alloy. Compared to pure metals, these alloy nanocatalysts are more active toward CO and methanol oxidation and nitrate reduction reactions. Nanoparticles made of PtRu, PtIr, PtNi, AuCo, AuCu, and FeCo bulk alloys demonstrate the universality of this synthesis method.